Method and apparatus for separating number of samples displaced in a tubing of small internal diameter



3,472,627 METHOD AND APPARATUS FOR SEPARATING NUMBER OF SAMPLES Oct. 14.1969 J. HRDINA DISPLACED IN A TUBING OF SMALL INTERNAL DIAMETER FiledMarch 30, 1966 '2 Sheets-Sheet l FIG. 8

INVENTOR.

Oct. 14,1969 J. HRDINA $472,627

METHOD AND APPARATUS FOR SEPARATING NUMBER OF SAMPLES DISPLACED IN ATUBING OF SMALL INTERNAL DIAMETER Filed March 50, 1966 2 Sheets-Sheet 2I NVEXTOR.

J [RI HR United States Patent US. Cl. 23-230 6 Claims ABSTRACT OF THEDISCLOSURE A first medium to be evaluated, such as amino acids, containsabsorbed therein a second medium and is led towards an evaluating devicein a tubing of small internal diameter passing a reactor. The pressureand/or heat conditions in the tubing within the reactor are adjusted torelease the absorbed second medium from the first medium by evaporationor by liquefying to separate segments of the first medium beforereaching the evaluating device.

This invention relates to a method and to an apparatus for separatingsamples of a medium delivered through a tubing of small internaldiameter for analyzing, dispensing or the like in an accordinglyoperating device.

'It is frequently required in laboratory practice to separate a numberof samples of some liquid or gaseous medium conveyed in a tubing ofsmall internal diameter in order to analyze or the like each of saidsamples separately without running the risk that the subsequentlyoperated on samples contaminate one another or even become mixed.

A method and an apparatus serving this purpose are described in the US.Patents Nos. 2,797,149, 2,879,141 and 3,047,367 permitting a number ofsuccessive analyses to be made in a continuous manner. The sample to beanalyzed is according to one embodiment pumped by a pump into a tubingof small internal diameter and the individual samples in the tubing areseparated by air bubbles introduced into said tubing by the pumpingaction of another pump so that air divides the fluid stream into asegmented fluid stream composed of alternate segments of liquid and air.In the course of travel of this segmented fluid stream through thetubing the segments of air displace liquid from the internal surface ofthe tubing so as to prevent or substantially reduce the mixing ofsamples with each other and hence prevent the contamination of onesample by another in the course of operation of the apparatus analyzingsubsequently a series of separated samples.

Alternately another liquid immiscible with the analyzed samples isintermittently introduced into said tubing with a similar eifect aspreviously described.

It is an object of this invention to simplify the separation of thedifferent samples of a medium displaced in a tubing of small internaldiameter.

In accordance with this invention a second medium capable to be adsorbedin the displaced first medium is used for separation of samples. Thesecond medium is according to this invention caused to be released fromsaid first medium during its passage through a tubing, creating thereinalternate segments of samples of the first medium and segments of thesecond medium which prevent or at least substantially reduce mixing ofdifferent segments of samples of the first medium.

In this specification the expression tubing of small internal diameterindicates a tubing which is capable 3,472,627 Patented Oct. 14, 1969 toretain intact bubbles or balls of the second medium separating samplesof the first medium in the course of displacement of the media. Inpractice the upper limit of the internal diameter of such a tubing is upto about one eighth of an inch.

Up to the present, liquid samples which had to be analyzed, have beendeliberately deaerated in order to prevent any creation of air bubbleswhich are segregated particularly at parts of the tubing maintained atelevated temperatures. Contrary thereto according to this invention thetreated samples of a fluidal medium to be evaluated and containingabsorbed air or some other inert gas are not deaerated, and bubbles ofair or gas are released in said tubing when the temperature is raised orthe pressure reduced so that the stream of liquid is divided into anumber of segments separated by air or gas bubbles. in a similar waygaseous samples can be separated by balls or bubbles of the secondmedium which liquefies in case pressure is increased or temperature isreduced.

FIG. 1 of the accompanying drawings illustrates the method of thepresent invention in its simplest embodiment applying a gaseous mediumfor separation of samples of a liquid medium using heat for the releaseof gas bubbles.

FIG. 2 is an alternative arrangement using in addition reduced pressureto release gas bubbles,

FIG. 3 is a similar arrangement,

FIG. 4 shows a pressure reducing valve used for this urpose.

FIG. 5 shows a space of reduced pressure connected to the outlet of thetubing; and

FIG. 6 shows the introduction of an evaluating reagent to the outlet ofa chromatographic column.

According to FIG. 1 a liquid having air or inert gas absorbed is pumpedby the pump 3 through the tubing 4 of small internal diameter, the part1 of said tubing which is immersed in a bath 2 contained in a reactorvessel heated to a temperature at which bubbles of air or gas absorbedin the liquid are released. The thus separated parts of the liquid aredisplaced by Way of an outlet tubing 6 to an evaluating device 5.

According to FIG. 2 the desorption eflect of the bath is increased byplacing the pump 3 below the part 1 of the tubing, thus creating reducedpressure at the input to part 1 of the tubing with respect to thepressure at the outlet of the pump 3 due to the hydrostatic elfect.

According to FIG. 3 said reduced pressure between the input and outputof part 1 of the tubing is achieved by placing the outlet 7 of thetubing 7 behind the evaluating device 5 deeper than the part 1 of thetubing.

According to FIG. 4 a reduction in pressure causing desorption of gasbubbles is caused by a pressure reducing valve 8 in tubing 4 behind thepump 3 whereas in front of the pump 3 conditions prevail at whichdesorption does not take place.

According to FIG. 5 the outlet tubing 7 behind the evaluating device 5is connected to a space 9 wherein reduced pressure is maintained.

FIG. 6 shows schematically the application of the object of thisinvention in connection with a chromatographic analyzer of a liquid. Theliquid to be analyzed, for instance a mixture of amino acids is pumpedby the pump 3 to the chromatographic column 11 containing reagents whichcause the difierent phases of the mixture to be displaced in thechromatographic column 11 at different rates. The evaluating reagent,for example ninhydrin is added to the outlet conduit of thechromatographic column 11 by means of the pump 12 to the junction 10.The separated amino acids together with the evaluating reagent proceedin tubing 4 to part 1 of the tubing immersed in the bath 2, wherebubbles are released; these bubbles divide the up to this momentcontinuous stream of liquid into a number of segments and prevent in thecourse of the subsequent passage any mixing of the different phases ofthe liquid separated in the chromatographic column 11. The thusseparated phases are evaluated in the evaluation device 5.

It is understood that the part 1 of tubing 4, Where the desorption ofbubbles takes place, is arranged as close as possible to the outlet ofthe chromatographic column 11 in order to reduce to the possibly highestdegree any decrease of concentration gradients in the liquid leaving thechromatographic column 11. In a similar way the method according to thisinvention can be applied in other cases, where a number of samples haveto be in succession analyzed, for instance difierent samples of urea orblood or for continuous checking of certain conditions in the course ofsome operation.

As has been already stated, gaseous media can be treated in a similarmanner by releasing for instance in part 1 of the tubing 4 balls ofwater which were prior evaporated and which separate the differentsamples of the gaseous medium. In that case the bath 2 has to operate ata reduced temperature or at an increased pressure.

A rather important contribution of this invention is the omission of thedeaeration of liquids prior to their analyzing. Up to the present theformation of bubbles in the course of heating a liquid which had to beperformed prior to its analysis has been rather troublesome and theremoval of air absorbed in the liquid generally not sufficientlyeffective. According to this invention the desorption of gases whichparticularly takes place in the course of heating of the analyzed liquidis utilized for separating successive samples, so that the up to nowtroublesome operation rendering a rather poor effect is not requiredanymore.

I claim:

1. The method of segmentizing samples of a first fluid medium to beevaluated, comprising the steps of absorbing a second fluid medium inthe first fluid medium, passing the thus combined fluid media through atubing of small internal diameter, a portion of the tubing beingimmersed in a heated reactor, and selectively adjusting at least one ofthe pressure and the heat conditions existing in the portion of thetubing within the reactor to release the second medium from the firstmedium, whereby the second medium forms separating segments betweenresulting segments of the first medium, and the thus separated segmentsmay be passed into the evaluating device.

2. The method according to claim 1 wherein the second medium is releasedin gaseous form from the first medium by increase of the heat.

3. The method according to claim 1 wherein the second medium is-releasedin gaseous form from the first medium by reduction of pressure.

4. The method according to claim 1 wherein the second medium is releasedin liquefied form from the first medium by reduction of heat.

5. The method according to claim 1 wherein the second medium is releasedin liquefied form from the first medium by increase of pressure.

6. In a device to separate samples of a first fiuidal medium, containingan absorbed second fiuidal medium for evaluating in an evaluatingdevice, the improvement comprising in combination a source for saidfirst medium containing an absorbed second medium; pumping means and anadjoining tubing of small internal diameter carrying said media througha heat reactor into said evaluating device; an exit tubing leading fromsaid evaluating device; and means to selectively adjust at least one ofthe pressure and heat conditions in the tubing within the reactor torelease the second medium from the first medium whereby the secondmedium forms separating segments between resulting segments of the firstmedium, and the thus separated segments may be passed to an evaluatingdevice.

References Cited UNITED STATES PATENTS 2,946,665 7/1960 Skeggs 23-2303,047,367 7/1962 Kessler 23-230 3,097,927 7/1963 Skeggs 23-230 OTHERREFERENCES Hawk, Oser & Summerson, Practical Physiological Chemistry,13th edn. McGraw-Hill, QP 514 H4, 1954. Copy in Gp. 170, pp. 129, 130,892 and 893 relied on.

MORRIS O. WOLK, Primary Examiner R. M. REESE, Assistant Examiner US. Cl.X.R.

